Image recorder with microstep driven motor transport

Abstract

An image forming apparatus for forming in series a plurality of images on a photosensitive film of the long roll type having a film transporting mechanism using a stepping motor, a microstep driver for controllably driving the stepping motor in a plurality of microsteps constituting one step unit of the stepping motor and an imaging device for forming an image on the film being transported by the film transporting mechanism. According to this image forming apparatus, variations in the film transport start positions resulting from the microstep-wise drive are avoided either by the film transporting mechanism arranged such that a pitch between adjacent images to be formed in series on the film is a multiple of an integer of a film transport distance covered by the single step unit of the stepping motor, or by an initial control device for re-setting the stepping motor to a stop position thereof assumed at completion of a previous imaging operation before re-energizing the stepping motor for a next imaging operation.

What is claimed is: 
     
       1. An image forming apparatus for forming in series a plurality of images on a photosensitive film of the long roll type comprising: feeding means for feeding the film;   discharging means for discharging an image-recorded film;   transporting means interposed between said feeding means and said discharging means for transporting the film from said feeding means to said discharging means;   a stepping motor for driving said transporting means;   a microstep driver for controllably driving said stepping motor in a plurality of microsteps constituting one step unit of said stepping motor;   imaging means for scanning and exposing the film being transported by said transporting means in a direction normal to a film transporting direction;   wherein a pitch between adjacent images to be formed in series on the film is a multiple of an integer of a film transport distance covered by the single step unit of said stepping motor;   said transporting means includes a platen roller driven and rotated by said stepping motor, said platen roller having a diameter predetermined to be of a multiple of an integer value of said film transport distance covered by one step unit of said stepping motor; and   wherein said platen roller is mounted on a drive shaft of said stepping motor, said diameter: R of the platen roller, said pitch: P of the adjacent images to be formed in series on the film being represented by the following expression:   R=(1/N)×(P/π)×(360/A)     where N is an integer value and A is a step angle of said stepping motor.     
     
     
       2. An image forming apparatus for forming in series a plurality of images on a photosensitive film of the long roll type comprising: feeding means for feeding the film;   discharging means for discharging an image-recorded film;   transporting means interposed between said feeding means and said discharging means for transporting the film from said feeding means to said discharging means;   a stepping motor for driving said transporting means;   a microstep driver for controllably driving said stepping motor in a plurality of microsteps constituting one step unit of said stepping motor;   imaging means for scanning and exposing the film being transported by said transporting mean in a direction normal to a film transporting direction whereby when an imaging operation is completed, a stop position for said stepping motor is determined; and   initial control means for re-setting said stepping motor to said stop position determined at the completion of the immediately preceding imaging operation before re-energizing said stepping motor for a next imaging operation.   
     
     
       3. An image forming apparatus, as defined in claim 2, further comprising: memory means for storing a number of microsteps corresponding to a film transport distance provided by said platen roller;   wherein said initial control means executes an initial control operation on said stepping motor in accordance with said number of microsteps stored in said memory means.   
     
     
       4. An image forming apparatus, as defined in claim 2, wherein said microstep driver supplies a current to said stepping motor for the microstep drive of the stepping motor such that changes in the supplied current are phased in over a predetermined period of time.